The present invention is related to Japanese patent application No. Hei. 11-357627, filed Dec. 16, 1999; 2000-316455, filed Oct. 17, 2000, the contents of which are incorporated herein by reference.
The invention relates to a control device for a vehicular AC generator, and more particularly, to a control device for a vehicular AC generator having a connector with an electromagnetic wave noise preventing function.
In recent years, there has been an increase in high frequency electromagnetic field in vehicles as portable telephones and navigation systems prevail.
Since influences given to electronic equipment by electromagnetic waves of a particular intensity increase with an increase in frequency, there is a demand to reduce adverse influences given to a control device for a vehicular AC generator, by high frequency radio waves used in portable telephones or the like. At the same time, there is a demand to reduce adverse influence given to on-board electronic devices, the above-mentioned portable telephones and navigation systems, by electromagnetic wave noises, which are generated from a control device (also, referred to as a regulator) for a vehicular AC generator. Much of these electromagnetic wave noises flows through wiring inside and outside the electronic devices and adversely affects the operation of elements in the electronic devices. Such wiring inducing noises are called hereinafter line superposed noises.
It has been conventionally known to mount and connect ferrite ring cores, feed-through capacitors, bypass capacitors or the like to wiring to reduce such line superposed noises. These elements constitute a low-pass filter composed of line inductance or wiring resistance and bypass capacitance including parasitic capacitance, and shut off or reduce high frequency electromagnetic wave noises.
For example, Japanese Patent Laid-Open No. 190620/1993 proposes a connector having an electromagnetic wave noise preventing function and housing therein or fixing integrally thereto a cylindrical-shaped noise absorbing member, which surrounds terminals of the connector and comprises ferrite ring cores or feed-through capacitors.
Also, Japanese Patent Laid-Open No. 29042/1993 proposes pressure fitting and fixing ferrite ring cores to a wall portion of a housing to have the ferrite ring cores surrounding terminals of a connector fixed to the wall portion.
Further, Japanese Patent Laid-Open No. 115737/1995 proposes suppressing entry of electromagnetic wave noises from a L terminal by providing a bypass capacitor between a pair of positive and negative input ends of a comparator for comparison and determination of battery voltage fluctuations of a control device (referred below to as a regulator) for a vehicular AC generator.
A conventional regulator for a vehicular AC generator comprises an output circuit unit including a switching transistor connected at one end thereof to one end of a battery through a field coil of the vehicular AC generator and at the other end thereof to the other end of the battery. This regulator performs intermittent control of current conducted to the field coil. An internal electric source circuit unit is supplied with electricity from the battery to form an internal electric source voltage. A switching transistor control circuit unit is actuated by the internal electric source voltage and performs intermittent control of the switching transistor based on battery voltage and a predetermined target voltage. A battery voltage supplying terminal is connected to a high potential end of the battery for supplying electricity to the internal electric source circuit unit via an internal electric source line. A battery voltage detecting terminal is connected to a high potential end of the battery for permitting voltage of the battery to be input into the switching transistor control circuit unit through an internal battery voltage detection line. An IG ON detection terminal connected to one end of an ignition switch to permit voltage change caused by the ignition switch to be input into the switching transistor control circuit unit through an IG ON detection line. The control device is fixed to the vehicular AC generator.
Experiments performed by the inventors of this application have revealed that with the constitution disclosed by the above-mentioned Japanese Patent Laid-Open No. 115737/1995, in which a bypass capacitor is used to reduce electromagnetic wave noises entering from a L terminal serving also as an IG terminal of a regulator, the effect of reducing entry of electromagnetic wave noises into the regulator is restricted, and such constitution is not effective in reduction of electromagnetic wave noises generated from the regulator. This is because the regulator includes a number of wires and thus paths of entry and irradiation of electromagnetic wave noises from the regulator.
Of course, if ferrite ring cores and bypass capacitors are provided for all wires of the regulator, it is possible to reduce electromagnetic wave noise entering the regulator via these wires. However, the provision of ferrite ring cores and bypass capacitors on all wires of a regulator mounted on an on-board vehicular AC generator is impossible in terms of cost and allowable installation space. In particular, since a regulator mounted on a vehicular AC generator disposed near an internal combustion engine is used during high temperature and intense vibrations, bypass capacitors of large capacity with an adequate noise reducing performance must have heat resistant and vibration resistant qualities and be large in size, which presents a further problem in terms of cost and an installation space.
It is therefore an object of the present invention to provide a control device for a vehicular AC generator, preventing entry of electromagnetic wave noises while suppressing an increase in physical dimensions, and a connector suitable for application to the device.
A control device for a vehicular AC generator, in a first aspect comprises a field current switching circuit unit having a switching transistor switching current conducted to a field coil, a switching transistor control circuit unit for performing intermittent control of the switching transistor based on a battery voltage and a predetermined target voltage, an internal electric source circuit that uses electricity supplied from the battery to form an internal electric source voltage applied to the switching transistor control circuit unit, a casing containing ICs mold-sealed by the respective circuit units, a battery voltage supplying terminal for supplying electricity to the internal electric source circuit unit from the battery via an internal electric source line, and a magnetic body mounted to the internal electric source line or the battery voltage supplying terminal, and in the control device, the battery voltage supplying terminal and the magnetic body are fixed to the casing.
A second aspect of the invention uses a field current switching circuit unit having a switching transistor for performing switching control of current conducted to a field coil, a switching transistor control circuit unit for performing intermittent control of the switching transistor based on a battery voltage and a predetermined target voltage, an internal electric source circuit unit for using electricity supplied from the battery to form an internal electric source voltage being applied to the switching transistor control circuit unit, a casing containing therein ICs mold-sealed by the respective circuit units or the respective circuit units, a battery voltage supplying terminal for supplying electricity to the internal electric source circuit unit from the battery via an internal electric source line, and an inductance element connected in series to the internal electric source line. In the control device, the battery voltage supplying terminal and the inductance element are fixed to the casing.
Another aspect of the invention comprises a battery voltage detecting terminal connected to a high potential end of the battery for permitting voltage of the battery to be input into the switching transistor control circuit unit through a battery voltage detection line, and a high frequency bypass capacitor connecting between the battery voltage detection line or the battery voltage detecting terminal and a potential source at a potential equal to a negative potential of the battery. The battery voltage detecting terminal and the high frequency bypass capacitor are fixed to the casing.
In the above described aspect, magnetic bodies for reduction of electromagnetic wave noises are mounted to a battery voltage supplying terminal (BR terminal) for supplying of an electric source power for the operation of circuits to a regulator (in particular, its switching transistor control circuit unit) or an internal electric source line for connection of the terminal to an internal circuit of the regulator. They are also connected to an IG ON detection terminal (a conventional IG terminal or a L terminal (also detecting opening and closing of an ignition switch)) for inputting into the regulator (in particular, its switching transistor control circuit unit) a voltage signal caused by opening and closing of the ignition switch or to an IG ON detection line for connection of the detection terminal to the switching transistor control circuit unit of the regulator. A bypass capacitor is connected to a battery voltage detection terminal (S terminal) for inputting a change of battery voltage into the switching transistor control circuit unit of the regulator. The capacitor can be connected to a battery voltage detection line for connection of the terminal to the switching transistor control circuit unit of the regulator, whereby marked reduction of receiving or irradiating (through wiring) of electromagnetic wave noises on the regulator as compared with the prior art can be realized while suppressing physical dimensions and an increase in cost with respect to the regulator.
That is, the bypass capacitor (including a feed-through capacitor) is arranged on the S terminal or on internal battery voltage detection line for connection of the S terminal to the switching transistor control circuit unit of the regulator.
For electromagnetic wave noises entering the regulator from the S terminal, the S terminal is connected via an internal electric source line to a comparator for comparing voltage (comparison between a reference voltage and a battery voltage input from the S terminal), having a high input impedance. In addition, voltage division is sometimes effected in a voltage divider circuit before the voltage is input into the comparator from the S terminal.
Where an external line for connection of the S terminal with the battery voltage is a high frequency noise electric source, load impedance of the high frequency noise electric source composed of resistance of the voltage divider circuit or input impedance of the comparator is fairly large. Therefore, a bypass capacitor is connected thereto in parallel, whereby most of high frequency electromagnetic wave current is made to easily flow through the bypass capacitor. This enables bypassing. This is because the S terminal is a signal terminal to be connected to load of relatively high resistance in the regulator.
In contrast, a case will be considered, in which a ferrite ring core is connected to the S terminal or the internal battery voltage detection line connected thereto. In this case, the ferrite ring core acts to increase wiring inductance connected to the load of relatively high resistance, but there are problems that since the load is relatively large, noise reduction effect cannot be obtained unless the wiring inductance is made considerably great, and that a change in battery voltage is divided by the load and the increased wiring inductance to lead to reduction in the change in battery voltage, input into the load.
That is, in order to reduce electromagnetic wave noises entering from the S terminal while detecting a change in battery voltage with good follow-up quality, it is found that employment of a bypass capacitor rather than a ferrite ring core (magnetic body) is preferable.
Since the BR terminal supplies an electric source current to the regulator, it follows in terms of an equivalent circuit that electromagnetic wave noise voltage electromagnetically or electrostatically induced to an external line for connection of the BR terminal and the battery is applied to a relatively small load of the regulator. Accordingly, a magnetic body is mounted to the BR terminal or an internal electric source line contiguous thereto to provide an increase in wiring inductance, and then much of electromagnetic wave noise voltage is consumed thereby, and does not enter into the regulator. Also, since the BR terminal does not need transmission of a signal due to transmission of a voltage change, it is unnecessary to take account of attenuation in signals.
In contrast, where a bypass capacitor is connected in parallel to the relatively small load, capacity or impedance of the bypass capacitor must be markedly increased as compared with the above-mentioned bypass capacitor on the S terminal, which develops a problem that the bypass capacitor is caused to markedly increase in physical dimensions.
The IG terminal (a L terminal is regarded as an IG ON detection terminal referred to in the invention in the case where voltage change due to opening and closing of the ignition switch is received through the L terminal) suffices to drive a markedly small load as compared with input impedance of the regulator connected to the S terminal, and like the BR terminal, an increase in wiring inductance, due to the magnetic body is more effective than a decrease in bypass impedance in parallel to input impedance of the regulator, caused by the bypass capacitor. Also, that attenuation in transmission signal amplitude associated with the IG terminal, which is caused by an increase in wiring inductance, due to the magnetic body, shall not interfere with start of the circuit operation because opening and closing signals of the ignition switch, due to opening and closing of the ignition switch, input from the IG terminal are exceedingly large (equal to the battery voltage) in amplitude.
Since the L terminal is actuated by a lamp drive transistor in the regulator, and is also an output impedance of the regulator, even when electromagnetic wave noise voltages are superposed on a wiring leading to the battery from the L terminal via a charge lamp, part of electromagnetic wave noise voltage is consumed by the charge lamp, and the remainder of the voltage is also consumed through a small ON resistance of the lamp drive transistor, whereby no problem is caused. There is a path, along which electromagnetic wave noises enter into the regulator by way of a parasitic capacitance between a primary electrode and a control electrode of the lamp drive transistor on the side of the L terminal, but that matters little since such parasitic capacitance is small.
Since the F terminal is connected to a terminal of the battery through a field coil and an external wiring of an outside vehicular AC generator and is attached to the other terminal of the battery through a small ON resistance of the switching transistor of the regulator, much of electromagnetic wave noise voltages superposed on the external wiring is born by the field coil, and will not enter into the regulator.
The P terminal is connected to an armature coil of an outside vehicular AC generator through an external wiring, and the cooling fins and a housing of a vehicular AC generator are strangely shaped and large-sized, and are exceedingly small in electric resistance. Magnetic bodies are mounted to a battery voltage supplying terminal and an IG ON detection terminal, which constitute terminals of a connector on the casing. With such arrangement, mounting of magnetic bodies is made simple as described later.
In another aspect, the magnetic body is disposed closer to the internal electric source circuit unit than a connection between the battery voltage supplying terminal and the field coil to be mounted to the battery voltage supplying terminal or the internal electric source line.
In another aspect of the invention, the magnetic body is embedded in a connector portion of a resin provided integrally on the casing of a resin. Such embedding can be carried out by a well-known manufacturing method such as insert molding and mold molding.
In another aspect, the magnetic body is received in a magnetic body receiving groove formed in a concave manner on a bottom surface of the connector portion of a resin provided integrally on the casing of a resin.
In another aspect, a peripheral wall of the connector portion facing the magnetic body receiving groove comprises a rib, which narrows an opening of the groove, and the peripheral wall (outer peripheral wall portion) and the rib (projection) elastically deform in a direction, in which the opening of the groove is enlarged to an extent permitting passage of the magnetic body upon insertion of the magnetic body into the groove.
In another aspect of the invention, the magnetic body is formed from an electrically conductive, magnetic material to be electrically insulated by the casing of a resin or the connector portion of a resin, for example, from the terminals.
In another aspect, the battery voltage supplying terminal or the IG ON detection terminal is flat-plate shaped, of which a cross section in a direction perpendicular to a lengthwise direction is substantially rectangular in shape, and the magnetic body has a slot.
In another aspect, the magnetic body has a slot, through which a ring-shaped tip end of the battery voltage supplying terminal extends, so that while suppressing an increase in magnetic path length, it is possible to post-mount the magnetic body.
In another aspect, the magnetic body has a plurality of through holes, through which a plurality of terminals extend separately, so that while suppressing leakage of electromagnetic signals between the respective terminals, it is possible to reduce the whole physical dimensions of the magnetic body and an amount of a magnetic body used. Also, a magnetic body can be embedded in a connector portion to surround terminals (connector pins), the connector portion being ordinarily formed from a resin to support bases of the terminals (connector pins). In addition, the term xe2x80x9cembeddingxe2x80x9d referred to in the specification of this application includes the case where the magnetic body is exposed from the connector portion to an extent that the magnetic body does not easily drop off as well as the case where the magnetic body is fully surrounded by the connector portion.
In another aspect, the magnetic body is formed from an electrically conductive, magnetic material to be electrically insulated from the terminal by the connector portion, so that the connector portion for supporting of terminals can serve also to provide an electric insulating function between the terminals and the electrically conductive, magnetic material, and an electrically conductive material can be used for the magnetic body while complexity in the manufacturing process and construction is suppressed. Further, reduction in electromagnetic wave noises caused by eddy current loss of the magnetic body can be realized.
In another aspect, the terminal comprises an electric source wiring for supplying of an electric source power to the circuit parts in the casing. That is, the electrically conductive, magnetic material does not specifically need transmission of sharp signal voltages and prevents magnetic saturation of the magnetic body due to large magnetic flux caused by a large change in electric source current, so that application to electric source wires is most preferable. Also, the magnetic body is pressure can be fitted in a magnetic body receiving groove formed in a concave manner on a bottom surface of the connector portion.
In another aspect, a peripheral wall of the connector portion facing the magnetic body receiving groove comprises a rib, which narrows an opening of the magnetic body receiving groove, and the peripheral wall and the rib have an elastic deforming characteristics in a direction, in which the opening permitting insertion of the magnetic body into the magnetic body receiving groove is enlarged. Therefore, a magnetic body supporting quality of the connector portion can be further improved, and manufacture is made simple owing to ease, with which a die is taken out. The magnetic body can have a slot is mounted to a flat-plate terminal, so that it is possible to realize a magnetic body of a small size having a large inductance.
In another aspect, the terminal has a head, which is larger in width than the base, and the magnetic body has a slot, through which the head of the terminal can extend. Therefore, it is possible to avoid an increase in physical dimensions of the magnetic body while suppressing a decrease in inductance, due to an increase in magnetic path length of the magnetic body. The plurality of terminals can extend separately through a plurality of through holes in the magnetic body.
In another aspect, the connector portion comprises a resin molded part, in which electrically insulating, magnetic particles are dispersed and filled, and so the connector portion itself constitutes a magnetic body. Therefore, it is possible to obtain a large inductance with manufacture being simple and without an increase in physical dimensions of the magnetic body, and to obtain an excellent electromagnetic wave noise shut-off effect.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In the drawings: